Tom Harris, also known as The Hill Country Gardener, is a Master Gardener certified by the State of Texas, a Master Pruner certified by the San Antonio Botanical Garden, and a founder and volunteer for the Gardening Volunteers of South Texas (GVST).

Note: This is an mySA.com City Brights Blog. These blogs are not written or edited by mySA or the San Antonio Express-News. The authors are solely responsible for the content.

Tom Harris: Please Don’t “Top” Your Trees

Why? There are lots of reasons — which I’ll explain in a minute — but the main reason is that it’s just plain ol’ ugly … with a capital U. If you’ve hired a tree trimmer who wants to do it, tell him you’ve changed your mind and that you’re going to hire a LICENSED tree trimmer or arborist.

There are many reasons for pruning trees and other plants. Dr. Jerry Parsons pointed out in a recent article that, “Pruning for the following reasons will help prolong the plant’s life by: (1) removing dead or dying portions of plant with disease problems or insect injury, (2) removing portions of plant injured or killed by the winter, (3) removing branches injured by storms, (4) removing existing branch stubs, (5) removing rubbing branches, (6) removing sprouts or suckers at the base of grafted plants, (7) removing water sprouts (succulent vigorous shoots on the inside of the tree near the trunk), (8) removing surplus branches so the remaining ones are spaced at 1 foot apart on trees, (9) branches normally should be left so they come out from all sides of the tree, (10) removing narrow-angled branches from the main trunk.”

The International Society of Arboriculture states that topping can be defined as “the indiscriminate cutting of tree branches to stubs or lateral branches that are not large enough to assume the terminal role.” The ISA also calls it “heading,” “tipping,” “hat-racking,” and “rounding over.”

There are many reasons not to top a tree — regardless of what it looks like. First, it stresses the tree because topping removes most, it not all, of the leaves. The leaves are used to manufacture food for the tree and they send this food down the trunk to the roots and the roots modify the food and send it back up. If a tree doesn’t have any leaves due to topping, the latent buds on the branches will go into the panic mode and try to put on as many leaves as possible in the shortest time possible. This typically creates fast-growing limbs that are pretty weak and subject to breakage in the wind–even small winds.

The ISA identifies, “Branches within a tree’s crown produce thousands of leaves to absorb sunlight. When the leaves are removed, the remaining branches and trunk are suddenly exposed to high levels of light and heat. The result may be sunburn of the tissues beneath the bark, which can lead to cankers, bark splitting, and death of some branches.”

“The survival mechanism that causes a tree to produce multiple shoots below each topping cut comes at great expense to the tree. These shoots develop from buds near the surface of the old branches. Unlike normal branches that develop in a socket of overlapping wood tissues, these new shoots are anchored only in the outermost layers of the parent branches. The new shoots grow quickly, as much as 20 feet in one year, in some species. Unfortunately, the shoots are prone to breaking, especially during windy conditions. The irony is that while the goal was to reduce the tree’s height to make it safer, it has been made more hazardous than before. “The cost of topping a tree is not limited to what the perpetrator is paid. If the tree survives, it will require pruning again within a few years. It will either need to be reduced again or storm damage will have to be cleaned up. If the tree dies, it will have to be removed.”

“Topping is a high-maintenance pruning practice, with some hidden costs. One is the reduction in property value. Healthy, well-maintained trees can add 10 to 20 percent to the value of a property. Disfigured, topped trees are considered an impending expense.”

“Another possible cost of topped trees is potential liability. Topped trees are prone to breaking and can be hazardous. Because topping is considered an unacceptable pruning practice, any damage caused by branch failure of a topped tree may lead to a finding of negligence in a court of law.”

Do not attempt to prune near electrical and utility wires. The utility companies should be contacted to do that kind of work.

Parsons also points out that for most landscapes, the natural form of the plants is best, and consequently plants should not be sheared to tight geometrical forms. They should be altered only if the plant must be confined or trained to a specific purpose. After pruning, it should not be obvious that the plant has been pruned. Never leave stubs because these serve as entryways for disease organisms to invade the plant.